Employing neurophysiological and psychophysiological techniques in man, cat, and monkey, interrelationships will be sought between autonomic and central nervous system mechanisms and behavior. Particular emphasis will be placed on behavioral states of attention and response-intention, and on sensorimotor performance such as reaction time and perceptual accuracy. A wide variety of physiological measures will be employed, but emphasis is placed on event-related cerebral potentials, such as the contingent negative variation and the readiness potential, and on heart rate, blood pressure, oxygen consumption, and skeletal activity. Newly discovered interacting effects of cardiac phase and respiratory phase will be studied in detail, and cardiac pacemaker response curves will be determined in intact humans by a non-invasive and innocuous technique. The role in behavior of visceral afferent feedback from the cardiovascular system to the central nervous system via the baroreceptor nerves will be evaluated experimentally, by pharmacological means and by interruption of baroreceptor pathways.